1. Field of Invention
The present invention relates to impact power tools and, more particularly, to hand-held, variable, hand pressure activated power tools that are used for delicate hand engraving and stone setting operations in the hand engraving and jewelry fields. In addition, dental and surgical fields that use pneumatic and ultrasonic scales used in the , as well as impact scribes for paleontology fossil recovery fields will benefit from the present invention.
2. Description of Prior Art
A hand-held impact power tool is known from U.S. Pat. No. 6,095,256 in the name of Steven Lindsay, which may be used for engraving, carving, and delicate stone setting operations. Although this known impact power graver provides improved control of delicate hand-working operations, it would be desirable to provide an impact power graver with a feature that will provide greater ease of use. The prior applications Ser. Nos. 09/754,889 and 09/876,434 in the name of Steven Lindsay filed on dates Jan. 5, 2001 and Jun. 7, 2001 respectively, U.S. Pat. No. 6,095,256 to Lindsay as well as U.S. Pat. Nos. 6,085,850, 5,803,183, 5,449,044, and 4,030,556, all to Phillips, as well as U.S. Pat. Nos. 5,515,930, 4,694,912 and 5,203,417 to Glaser, and U.S. Pat. No. 3,393,755 to Glaser et al. all employ the use of a foot pedal to control and operate a throttle for a hand held impact tool. The traditional hand engraving tool which has been in existence for centuries, consists of a tool bit (also known as a tool point or graver point) inset into a small round handle that is made to fit into the palm of the human hand. Because prior power assisted gravers mentioned use a foot control they are not natural for the traditional hand engraver who has learned palm push hand engraving. These highly skilled people as well as people beginning to learn to hand engrave have to learn to coordinate the foot throttle and hand motion when making an engraving cut with prior power gravers. With these prior power gravers it is important to only depress the foot control while holding the graver point in the cut. If the pedal is depressed when not held snuggly in the cut, there is a high possibility that the point of the graver will break and the cut will have chatter marks and burs. There is a need for a hand power engraving tool that is activated by the pressure of the person""s palm pushing the tool instead of using a foot control to activate the device. A palm push, variable power graver will prevent the tool being operated when not held in a cut and thus help those learning to engrave produce cleaner engraving cuts. The pressure activated power graver would need to be able to deliver very subtle, light impacts when the user is palm pushing lightly and it would need to deliver harder impacting power when greater force is exerted by the palm of the hand. The pressure would therefore need to activate the tool from an absence of power to much greater power and anywhere in between simply by the amount of pressure the user is creating with his or her palm on the tools handle. This type of device would also need to be user adjustable for the amount of force exerted by the person using it. One person may desire the tool to activate throughout a power range with very minimal palm pressure while another person may desire a harder variable palm pressure.
It is the object of this invention to provide a palm push hand engraving power tool that is activated from an absence of power to much greater power or anywhere in between simply by the amount of pressure exerted by the palm of hand on the tool""s handle. It is also an object of this invention to provide a hand engraving power tool that is natural for the user to operate. It is also an object that the invention can be utilized in a wider scope or field of use than merely the hand engraving and jewelry fields. Dental power scalers, including ultrasonic engravers and scalers, power surgical knives, impact scribes for paleontology fossil recovery and even larger hand held impact hammers used by artist for sculpturing and carving stone and marble may benefit from their tools being activated and adjustable in power by the pressure exerted on the tool with the hand.